A remarkable experiment has successfully seen the effects of “quantum motion” at a relatively large scale. These are essentially tiny vibrations caused on an atomic level when an object otherwise appears to be stationary. Among its many implications, the research – which was also able to temporarily stop the effect – could aid the hunt for elusive ripples in space-time called gravitational waves.
The study, published in the journal Science, was carried out by a team of researchers from the California Institute of Technology (Caltech) and collaborators. In classical physics, an object – such as a ball in a bowl – will eventually come to rest as the forces of gravity and friction act upon it. But in quantum mechanics, which governs the behavior of matter and light at an atomic scale, nothing is ever truly at rest.
This means that everything has an extremely small quantum noise, or motion; tiny vibrations at an atomic scale. In this experiment, the researchers were able to observe the effect not just at an atomic level, but at a larger micrometer-scale and, for the first time, control the effect.
To detect it, they placed a flexible aluminum plate on top of a silicon substrate. A superconducting electrical circuit was then used to vibrate the plate at 3.5 million times per second. Subsequently cooling the plate to 0.01 Kelvin (-273.14°C, -459.65°F) reduced the vibrations in a classical sense to zero, but probing it with microwave fields showed a small quantum motion – roughly the diameter of a proton, or 10,000 times smaller than a hydrogen atom.
“What we have found is that the motion of a micron scale object requires a quantum description,” co-author Keith Schwab from Caltech told IFLScience. “Classical physics just can’t capture the quantum noise we see.”
According to Schwab, the noise is an “unavoidable consequence of the Heisenberg Uncertainty Principle,” which essentially states that everything behaves like a particle and a wave at the same time. However, the team found that by carefully applying a controlled microwave field, they could reduce the motion in certain places, at the cost of making it much larger elsewhere. This technique is known as quantum squeezing.
Read more ~ IFL Science
Photo credit: agsandrew/Shutterstock.
Researchers at Duke University have developed a light-emitting device that can be switched on and off up to 90 billion times per second. This 90 GHz is roughly twice the speed of the fastest laser diodes in existence, potentially offering a whole new level of optoelectronic computing. Central to the technology are the infinitesimal crystal beads known as quantum dots.
The computing devices we’re used to are based on shuttling electrons around via wires and switches. This has worked out pretty well through the history of computing, but electronics have limits, both in speed and in scale. Optoelectronics swap out electrons for pure light: photons. A computer based on information carried via photon is just by definition optimal, offering the literal fastest thing in the universe. Other advantages over electronic systems: less heat, less power, less noise, less information loss, less wear.
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Peering at the debris from particle collisions that recreate the conditions of the very early universe, scientists have for the first time measured the force of interaction between pairs of antiprotons. Like the force that holds ordinary protons together within the nuclei of atoms, the force between antiprotons is attractive and strong.
The experiments were conducted at theRelativistic Heavy Ion Collider (RHIC), a U.S. Department of Energy Office of Science User Facility for nuclear physics research at DOE’s Brookhaven National Laboratory. The findings, published in the journal Nature, could offer insight into larger chunks of antimatter,including antimatter nuclei previously detected at RHIC, and may also help scientists explore one of science’s biggest questions: why the universe today consists mainly of ordinary matter with virtually no antimatter to be found.
“The Big Bang—the beginning of the universe—produced matter and antimatter in equal amounts. But that’s not the world we see today. Antimatter is extremely rare. It’s a huge mystery!” said Aihong Tang, a Brookhaven physicist involved in the analysis, which used data collected by RHIC’s STAR detector. “Although this puzzle has been known for decades and little clues have emerged, it remains one of the big challenges of science. Anything we learn about the nature of antimatter can potentially contribute to solving this puzzle.”
RHIC is the perfect place to study antimatter because it’s one of the few places on Earth that is able to create the elusive stuff in abundant quantities.
RHIC is the perfect place to study antimatter because it’s one of the few places on Earth that is able to create the elusive stuff in abundant quantities. It does this by slamming the nuclei of heavy atoms such as gold into one another at nearly the speed of light. These collisions produce conditions very similar to those that filled the universe microseconds after the Big Bang—with temperatures 250,000 times hotter than the center of the sun in a speck the size of a single atomic nucleus. All that energy packed into such a tiny space creates a plasma of matter’s fundamental building blocks, quarks and gluons, and thousands of new particles—matter and antimatter in equal amounts.
“We are taking advantage of the ability to produce ample amounts of antimatter so we can conduct this study,” said Tang.
The STAR collaboration has previous experience detecting and studying rare forms of antimatter—including anti-alpha particles, the largest antimatter nuclei ever created in a laboratory, each made of two antiprotons and two antineutrons. Those experiments gave them some insight into how the antiprotons interact within these larger composite objects. But in that case, “the force between the antiprotons is a convolution of the interactions with all the other particles,” Tang said. “We wanted to study the simple interaction of unbound antiprotons to get a ‘cleaner’ view of this force.”
To do that, they searched the STAR data from gold-gold collisions for pairs of antiprotons that were close enough to interact as they emerged from the fireball of the original collision.
“We see lots of protons, the basic building blocks of conventional atoms, coming out, and we see almost equal numbers of antiprotons,” said Zhengqiao Zhang, a graduate student in Professor Yu-Gang Ma’s group from the Shanghai Institute of Applied Physics of the Chinese Academy of Sciences, who works under the guidance of Tang when at Brookhaven. “The antiprotons look just like familiar protons, but because they are antimatter, they have a negative charge instead of positive, so they curve the opposite way in the magnetic field of the detector.”
“By looking at those that strike near one another on the detector, we can measure correlations in certain properties that give us insight into the force between pairs of antiprotons, including its strength and the range over which it acts,” he added.
The scientists found that the force between antiproton pairs is attractive, just like the strong nuclear force that holds ordinary atoms together. Considering they’d already discovered bound states of antiprotons and antineutrons—those antimatter nuclei—this wasn’t all that surprising. When the antiprotons are close together, the strong force interaction overcomes the tendency of the like (negatively) charged particles to repel one another in the same way it allows positively charged protons to bind to one another within the nuclei of ordinary atoms.
In fact, the measurements show no difference between matter and antimatter in the way the strong force behaves. That is, within the accuracy of these measurements, matter and antimatter appear to be perfectly symmetric. That means, at least with the precision the scientists were able to achieve, there doesn’t appear to be some asymmetric quirk of the strong force that can account for the continuing existence of matter in the universe and the scarcity of antimatter today.
But the scientists point out that we wouldn’t know that if they hadn’t done these experiments.
“There are many ways to test for matter/antimatter asymmetry, and there are more precise tests, but in addition to precision, it’s important to test it in qualitatively different ways. This experiment was a qualitatively new test,” said Richard Lednický, a STAR scientist from the Joint Institute for Nuclear Research, Dubna, and the Institute of Physics, Czech Academy of Sciences, Prague.
“The successful implementation of the technique used in this analysis opens an exciting possibility for exploring details of the strong interaction between other abundantly produced particle species,” he said, noting that RHIC and the Large Hadron Collider (LHC) are ideally suited for these measurements, which are difficult to assess by other means.
Brookhaven National Laboratory
Reid Wiseman Vines: That’s not the Sun, it’s the Moon setting on a gorgeous night.
Three quarks for Muster Mark*! And for every proton and neutron, too… right?
Not so fast. You might have learned that every proton and neutron is made of elementary particles called quarks, and that each of the familiar subatomic bits that make up the nucleus of atoms is built out of precisely three of the quirky, quarky sub-subatomic bunch.
This great video from The Physics Girl explains why that idea doesn’t quite add up to what’s really going on at matter’s smallest scales. Plus, CANDY! I love candy! Just wait ‘til you get to the part about how much mass is inside of a proton compared to the number of particles. Mind = blown, Einstein.
*Funny historical note: At the beginning of the video, Dianna asks why “quark” is spelled the way it is. It looks like it should be pronounced “kwahrk,” but we clearly pronounce it “kwork”. Well, Murray Gell-Mann, the physicist who first theorized the existence of these elementary particles, had already picked out the name he wanted, a made-up word that he pronounced “kwork”, but with no idea how he should spell it. Then, while reading Finnegan’s Wake by James Joyce, he stumbled on the following passage:
Three quarks for Muster Mark! Sure he has not got much of a bark And sure any he has it’s all beside the mark.
Gell-Mann stuck to his guns on the “kwork” pronunciation, despite the fact that it’s obviously supposed to rhyme with “Mark”, but seeing that Joyce had stumbled upon the same rule of three quarks that the universe had, he couldn’t pass it up. Quantum literature!
Scientists don’t fully understand quantum entanglement—but they know that space, or physical distance, is not a factor in the “communication” between two entangled particles. If one is affected by a force or a measurement, the other also reacts in the same moment, even if they are separated by leagues. Unlocking the secrets of this phenomenon could lead to incredible advancements in technology, such as quantum machines that transmit information faster than light.
Click the image above to learn more!
* (You look inside...) * (Inside the joke book is a quantum physics book.)
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